The use of electrical impedance tomography (EIT) to evaluate pulse rate in anaesthetised horses.
Authors: Raisis A L, Mosing M, Hosgood G L, Secombe C J, Adler A, Waldmann A D
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Electrical Impedance Tomography for Pulse Rate Measurement in Anaesthetised Horses Electrical impedance tomography (EIT) is increasingly recognised for producing clinically useful lung images during anaesthesia, but extracting reliable cardiovascular data from the same dataset would enhance its clinical utility considerably. Raisis and colleagues evaluated whether cardiac-related impedance changes detected by EIT could accurately quantify pulse rate across varying haemodynamic states—baseline, pharmacologically induced hypertension (nitroprusside), and hypotension (phenylephrine)—in seven anaesthetised horses positioned in dorsal recumbency. Their novel algorithm analysed impedance fluctuations in nine pixels representing the cardiac region over 10-second intervals and compared these measurements against concurrent invasive blood pressure tracings; 288 paired datasets from six horses demonstrated excellent agreement, with bias of only -0.26 beats per minute and limits of agreement between -2.22 and 1.69 beats per minute across all haemodynamic conditions. For equine practitioners, particularly anaesthetists and veterinary surgeons, this represents a non-invasive means of continuous pulse rate monitoring that remains accurate even during significant blood pressure perturbations—potentially reducing reliance on invasive monitoring whilst maintaining diagnostic precision. However, further validation is needed in other recumbencies and non-anaesthetised clinical situations before this technology can be confidently integrated into routine equine practice.
Read the full abstract on PubMed
Practical Takeaways
- •EIT offers a promising non-invasive monitoring tool for pulse rate assessment during equine anaesthesia, potentially reducing reliance on invasive monitoring techniques
- •The method maintains accuracy across different blood pressure states (normal, high, low), making it suitable for various anaesthetic protocols
- •Further validation needed in horses in different body positions and clinical settings before routine clinical implementation
Key Findings
- •EIT can accurately detect pulse rate from cardiac-related impedance changes in anaesthetised horses with a bias of -0.26 beats per minute
- •Excellent agreement between EIT-derived and invasive pulse rate measurements was demonstrated across baseline, hypertensive, and hypotensive states
- •Analysis of 288 paired datasets from six horses showed 95% limits of agreement between -2.22 and 1.69 beats per minute
- •EIT provides a non-invasive method to extract cardiovascular information alongside lung imaging during mechanical ventilation and apnoea